The present invention relates to a method for repairing a leaking pipe joint, particularly a bell and spigot joint.
Cast iron pipe is used extensively for water, gas, sewage, culverts, drains, etc., in a wide range of sizes and for varying pressures, and is particularly adapted to underground and submerged service because of its comparatively high resistance to corrosion. The pipe comes with either flanged ends or bell-and-spigot ends, the latter generally being used for underground work, making a tight joint when properly put together, caulked, and leaded. Flanged pipe has superior strength and tightness of joint and is used where the pipe can be well supported, the joints being made up with gaskets. The bell-and-spigot joint is more flexible, provides for expansion and contraction, and is therefore especially suitable for underground water and gas pipe.
Bell-and-spigot joints are generally caulked with oakum and sealed by pouring and caulking lead into the bell. Through the years, the oakum and lead by reason of internal pressure, vibration, temperature fluctuation, settling, road traffic and other causes may allow a leak. It then becomes necessary to expose and repair the joint. Traditionally this was done by repacking with new oakum and new lead, or applying a cement patch. Another method is to place a permanent mechanical compression member about a flexible seal on the joint. Other methods have been tried, such as placing a containment with an annular cavity around the joint and pouring molten metal into the containment to form a sealing collar. This could be accomplished by igniting thermite in a funnel mounted on the containment. This method, in addition to employing an almost violent reaction, did not always produce a good seal, since the metal could not be forced into the leaking joint and contracted on cooling. More recently, epoxy has been applied to joints by working it around the joint with a spatula, but this is somewhat troublesome and still does not provide positive pressure for working the epoxy into the joint.